Rating

< 1

0%

Extremely low risk associated with water quality and air quality, achieved using Dryden Aqua fully Integrated system operated properly with good overall hygiene and pool management. AFM, ZPM, APF, ACO and ZPMr. DIN standard Filters operating at less than 15 m/hr

1 - 1.9

2%

Very low risk associated with water quality and air quality, very good pool, fitted with AFM, ZPM and APF.  Filters operating at less than 20 m/hr

2 to 3.9

5%

Low risk pool but could do better. There may be high combined chlorine but no smell or sore eyes which indicates organic chloramine but low inorganic chloramines. Pool may be using AFM but flow rates are too high or poor quality filters are used. There may be equipment or operational problems. Filters operating at less than 25m/hr

4 to 4.9

15%

Low to medium risk pool, staff may experience respiratory issues, there will be a distinct smell of nitrogen trichloride, some of the public may complain about sore eyes.  There may be a risk to regular bathers.  Performance Factor is typical of sand filtration systems operating at water flows below 25 m/hr with poor coagulation and flocculation.

5 to 5.9

25%

Medium risk, staff may be at risk from respiratory issues. Some of the public will complain of sore eyes and skin irritation or allergic reactions. Regular users of the pool may be at risk from respiratory issues. Performance Factor is typical of sand filtration systems operating at water flows above 25 m/hr with poor coagulation and flocculation.

6 to 7.9

35%

Medium to High risk pool, staff and public are at risk, structural damage to the building and stainless steel may be evident.   High levels of trichloramine, probably also high levels of volatile lipid soluble organic and inorganic chlorine molecules such as chloroform and cyanogen chloride. Potential health risk to children under 2 years of age.

8 to 10

50%

High risk associated with using the pool or for the staff working in the pool environment. Potential bio-hazard from bacteria, oocysts, bacteria exotoxins and endotoxins. Public may experience an allergic response to the pool water and / or the atmosphere. Increasing potential risk of health problems especially for children under 2 years of age because their blood:brain barrier is not fully developed.

>10

+50%

Very high chlorine consumption indicative of a poor system design and operating conditions. In the opinion of Dryden Aqua any pools with a DAP Factor greater than 10 should be treated with extreme caution, especially for the pool staff, children, elderly or immune depressed individuals.  The water and air quality may be okay but only if the pool is exchanging or dumping large quantities of water. High chlorine demand may also be experienced with UV and ozone systems.